Glass or metal are the only materials I look for. Cheapass plastic or polycarbonate is a no no. Hell even the plastic edges/skeleton of the Z nearly put me off the Z but in the Android world there is no alternative.
I hate glass backed phones. They make the phone heavy, slippery, and are prone to cracks. I strongly prefer plastic of any sort over glass. That's just me.
So a pretty reputable XDA forum member named Spectre51 is stating that AT&T will not be offering the ZL. However it can be purchased unlocked of course from other sources and it will operate on AT&T's LTE network. FYI.